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Test universal hashing and fix bugs.
[mLib] / lock.h
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1/* -*-c-*-
2 *
3 * $Id: lock.h,v 1.2 1999/12/10 23:42:04 mdw Exp $
4 *
5 * Simplified POSIX locking interface
6 *
7 * (c) 1999 Straylight/Edgeware
8 */
9
10/*----- Licensing notice --------------------------------------------------*
11 *
12 * This file is part of the mLib utilities library.
13 *
14 * mLib is free software; you can redistribute it and/or modify
15 * it under the terms of the GNU Library General Public License as
16 * published by the Free Software Foundation; either version 2 of the
17 * License, or (at your option) any later version.
18 *
19 * mLib is distributed in the hope that it will be useful,
20 * but WITHOUT ANY WARRANTY; without even the implied warranty of
21 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
22 * GNU Library General Public License for more details.
23 *
24 * You should have received a copy of the GNU Library General Public
25 * License along with mLib; if not, write to the Free
26 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
27 * MA 02111-1307, USA.
28 */
29
30/*----- Revision history --------------------------------------------------*
31 *
32 * $Log: lock.h,v $
33 * Revision 1.2 1999/12/10 23:42:04 mdw
34 * Change header file guard names.
35 *
36 * Revision 1.1 1999/05/15 10:33:53 mdw
37 * Add simplified locking code.
38 *
39 */
40
41#ifndef MLIB_LOCK_H
42#define MLIB_LOCK_H
43
44#ifdef __cplusplus
45 extern "C" {
46#endif
47
48/*----- Magic constants ---------------------------------------------------*/
49
50enum {
51 LOCK_UNLOCK, /* Release a lock I obtained */
52 LOCK_EXCL, /* Obtain an exclusive lock */
53 LOCK_NONEXCL /* Obtain a nonexclusive lock */
54};
55
56/*----- Functions provided ------------------------------------------------*/
57
58/* --- @lock_file@ --- *
59 *
60 * Arguments: @int fd@ = file descriptor to lock
61 * @unsigned how@ = type of lock required
62 *
63 * Returns: 0 if OK, -1 if it failed.
64 *
65 * Use: Acquires a lock on the given file. The value @how@
66 * specifies the type of lock to acquire: @LOCK_EXCL@ gets
67 * an exclusive (write) lock; @LOCK_NONEXCL@ gets a non-
68 * exclusive (read) lock and @LOCK_UNLOCK@ releases any locks.
69 * Acquiring a lock gets timed out after a while with an
70 * error.
71 */
72
73extern int lock_file(int /*fd*/, unsigned /*how*/);
74
75/*----- That's all, folks -------------------------------------------------*/
76
77#ifdef __cplusplus
78 }
79#endif
80
81#endif